Spring Boot Step by Step Example



In this tutorial, we will learn how to develop a step by step Spring boot project. We will build a simple RESTFul web service application using Spring Boot. 

Let's create a Spring boot application step by step and we will build a simple REST API.

Step 1: Create Spring Boot Project in Eclipse STS IDE

Use the below guide to create a Spring boot project in Eclipse STS IDE:

Step 2: Packaging Structure

Following is the packing structure of this application for your reference-

Step 3: Maven pom.xml File

Use below pom.xml file for your reference:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>

 <groupId>net.javaguides.springboot</groupId>
 <artifactId>Springboot-helloworld-application</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <packaging>jar</packaging>

 <name>Springboot-helloworld-application</name>
 <description>Demo project for Spring Boot</description>

 <parent>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-parent</artifactId>
     <version>2.0.5.RELEASE</version>
     <relativePath/> <!-- lookup parent from repository -->
 </parent>

 <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <java.version>1.8</java.version>
 </properties>

 <dependencies>
     <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-web</artifactId>
     </dependency>

     <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-test</artifactId>
          <scope>test</scope>
     </dependency>
 </dependencies>

 <build>
     <plugins>
         <plugin>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-maven-plugin</artifactId>
         </plugin>
     </plugins>
 </build>
</project>

Step 4: Create Greeting DTO Class

To model the greeting representation, you create a resource representation class. Provide a plain old java object with fields, constructors, and accessors for the id and content data:
package net.javaguides.springboot.Springboothelloworldapplication;

public class Greeting {
    private final long id;
    private final String content;

    public Greeting(long id, String content) {
         this.id = id;
         this.content = content;
    }

    public long getId() {
        return id;
    }

    public String getContent() {
         return content;
    }
}
Spring uses the Jackson JSON library to automatically marshal instances of type Greeting into JSON.
Next, we create a resource controller that will serve these greetings.

Step 5: GreetingController

package net.javaguides.springboot.Springboothelloworldapplication;

import java.util.concurrent.atomic.AtomicLong;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class GreetingController {

    private static final String template = "Hello, %s!";
    private final AtomicLong counter = new AtomicLong();

    @RequestMapping("/greeting")
    public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
         return new Greeting(counter.incrementAndGet(), String.format(template, name));
    }
}

Step 6: Run Spring Boot Application

package net.javaguides.springboot.Springboothelloworldapplication;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringbootHelloworldApplication {

    public static void main(String[] args) {
         SpringApplication.run(SpringbootHelloworldApplication.class, args);
    }
}

From your IDE, run the SpringbootHelloworldApplication.main() method as a standalone Java class that will start the embedded Tomcat server on port 8080 and point the browser to http://localhost:8080/.

Or use the below command to run the Spring boot app:
$ mvn spring-boot:run
Now that the service is up, visit http://localhost:8080/greeting, where you see:
Provide a name query string parameter with http://localhost:8080/greeting?name=User. Notice how the value of the content attribute changes from "Hello, World!" to "Hello User!":

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